1. Technical Field
The present invention relates to the field of immunoassays for the detection of dextropropoxyphene. d-Propoxyphene [(2S:3R)-4-dimethylamino-1,2-diphenyl-3-methyl-2-propionoxybutane] is a mild narcotic analgesic, and is present as the active ingredient of the drug, Darvon.RTM.. d-Propoxyphene is metabolized primarily via N-demethylation to d-nor-propoxyphene and further demethylated to d-dinor-propoxyphene. Urinary excretion in the 20 h urine following a 130 mg single oral dose of propoxyphene expressed as % dose were 1.1% propoxyphene, 13.2% nor-propoxyphene and 0.7% dinor-propoxyphene (RE McMahon et al,"The Metabolite Pattern of d-Propoxyphene in Man," Life Sci Vol 12, 463-473, 1973). The half-life of d-nor-propoxyphene in urine has been reported to be 22 hours(S. B. Karch, "The Pathology of Drug Abuse", CRC Press, 1993, Chapter 5, pp 269). It is desirable that immunoassays be developed that have the specificity to detect both d-propoxyphene and d-nor-propoxyphene in biological fluids, particularly human urine. Due to the resemblance of propoxyphene to methadone, it is also preferable that the assay not detect methadone.
2. Background
U.S. Pat. No. 4,025,501 discloses immunogens derived from carboxy modified propoxyphene haptens that are useful in eliciting propoxyphene-specific antibodies. The exemplified structure of the immunogen employed to make antibodies was a hemisuccinate ester. The resultingly formed immunogenic protein conjugates thus had the peptide residue leashed off the carboxy modified oxyphene chain.
U.S. Pat. No. 5,239,086 discloses haptens and tracers for immunoassays for d-propoxyphene and d-nor-propoxyphene. Here again, the disclosed compounds are made by leashing out of a derivatized oxyphene chain. Exemplary immunogen and labeled derivatives have the structures shown below: ##STR1##